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Advanced
We recommend Reference Models, Architectures, Implementations- An Overview as prerequisite reading for this technology.
The Technical Architectural Framework for Information Management (TAFIM)
reference model was developed by the
Defense Information Systems Agency (DISA)
to guide the
evolution of Department of Defense (DoD) systems, including
sustaining base, strategic, and tactical systems, as well as interfaces to
weapon systems. Application of the TAFIM reference model is required on most
DoD systems
[Paige 93]. TAFIM is a set of services, standards, design
components, and configurations that are used in design, implementation, and
enhancement of information management system architectures. The intent is that
the DoD infrastructure will have a common architecture that will, over time,
be a fully
flexible and
interoperable enterprise. Details on the TAFIM
model are available in a seven volume TAFIM document, but are primarily in
Volume 3
[TAFIM 94].
The TAFIM reference model (Figure 27) describes services
(functionality) needed within each of the model's components. It contains a
set of general principles on how components and component services relate to
each other. This model is designed to enhance transition from legacy
applications to a
distributed environment. TAFIM addresses the following six software components:
- Application software. Application software consists of mission area applications and support applications. Mission area applications may be custom-developed software, commercial-off-the-shelf (COTS) products, or Non-developmental items (NDI). Support applications are building blocks for mission area applications. They manage processing for the communication environment and can be shared by multiple mission and support applications. Common COTS support applications include multimedia, communications, business processing, environment management, database utilities, and engineering support (analysis, design, modeling, development, and simulation) capabilities.
- Application platform. Application platform consists of
hardware services and software services, including operating system, real-time
monitoring program, and peripheral drivers. Application software must access
platform resources by a request across
Application Programming Interfaces (APIs) to ensure integrity and consistency. A platform service may be realized by a single process shared by a group of applications, or by a distributed system with portions of an application operating on separate processors. Application platform services include software engineering, user interface, data management, data interchange, graphic, network, and operating system capabilities.
- Application platform cross-area services. Application platform cross-area services are services that have a direct effect on the operation of one or more of the functional areas. Application platform cross-area services include culturally-related application environments, security, system administration and distributed computing capabilities.
- External environment. The external environment supports system and application interoperability and user and data portability. The external environment interface specifies a complete interface between the application platform and underlying external environment. The external environment includes human-computer interaction, information services, and communication capabilities.
- TAFIM application program interface (API).The API is the interface between an application and a service that resides on a platform. The API specifies how a service is invoked- without specifying its implementation- so that the implementation may be changed without causing a change in the applications that use that API. The API makes the platform transparent to the application. A platform may be a single computer or a network of hosts, clients, and servers where distributed applications are implemented. A service invoked through an API can reside on the same platform as the requesting application, on a different platform, or on a remote platform. APIs are defined for mission and support applications and platform services. APIs are generally required for platform services such as compilers, window management, data dictionaries, database management systems, communication protocols, and system management utilities.
- TAFIM external environment interface. The TAFIM external environment interface (which could be considered and API) is between the application platform and the external environment. This interface allows the exchange of information. It supports system and application software interoperability. User and data portability are directly provided by the external environment interface.
Figure 27: DoD TAFIM Technical Reference Model
The TAFIM reference model is applicable to most information systems, including
sustaining base, strategic, and tactical systems, as well as interfaces to
weapon systems
[TAFIM
94]. It is mandatory for use on most DoD programs
[Paige
93]. However, systems built using the reference model have been criticized
by Rear Adm. John Gauss, the Interoperability Chief at DISA, when speaking on
systems in the field in Bosnia: "We have built a bunch of state-of-the-art,
open-systems, TAFIM-compliant stove-pipes"
[Temin
96]. TAFIM-compliant means that the applicable standards and guidelines
are met for the implemented component services. This suggests that even when
complying with the TAFIM reference model, problems of interoperability are not
necessarily resolved. The Joint Technical Architecture (JTA) provides a set of
standards and guidelines for C4I systems, specifically in the area of
interoperability, that supersedes TAFIM Volume 7
[JTA 96].
There are TAFIM-compliant software products available for use when implementing a TAFIM-based architecture in areas such as support applications, communication services, business process services, environment management, and engineering services. Additional products exist or are being developed in areas such as user interface, data management, data interchange, graphics, operating systems, internationalization, security system management, and distributed computing.
The latest version of TAFIM, Version 2.0, was published in 1994. DoD
organizations and contractors have been applying this set of guidelines to
current and future information systems. The Defense Information Infrastructure Common
Operating Environment is an implementation of TAFIM. This COE is currently
being used by the
Global Command and Control System (GCCS) and the
Global Combat Support System (GCSS). The Air Force Theater Battle Management Core System (TBMCS) is also required to comply with the TAFIM and use the COE. It may take several years, after multiple new TAFIM-compliant systems are in the field, to determine the effectiveness of the reference model with respect to achieving a common, flexible, and interoperable DoD infrastructure.
The TAFIM reference model does not fully specify components and component
connections
[Clements 96]. It does not dictate the specific components for implementation. (No reference model prescribes implementation solutions.) TAFIM does provide the guidance necessary to improve commonality among DoD information technical architectures.
One contractor has found that there is no cost difference in using the TAFIM reference model (as compared to any other reference model) when designing and implementing a software architecture. This is based on the fact that application of a reference model is part of the standard design and implementation practice.
The TAFIM reference model is dependent on the evolution of component and service standards that apply specifically to software; it may be affected by computer platforms and network hardware as well.
Under conditions where the TAFIM reference model is not required, an
alternative model would be the Reference Model for Frameworks of Software
Engineering Environments (known as the ECMA model
[ECMA 93]) that is promoted
in Europe and used commercially and worldwide. Commercially-available
Hewlett-Packard products use this model
[HP 96]. Another alternative would be
the Common Object Request Broker Architecture (CORBA) if the design called for object-oriented infrastructure .
Open systems (see COTS and Open Systems-An Overview) would be a complementary technology to TAFIM because work done in open system supports the TAFIM goals of achieving interoperable systems.
This technology is classified under the following categories. Select a
category for a list of related topics.
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[Clements 96]
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Clements, Paul C. & Northrop, Linda M. Software Architecture: An
Executive Overview (CMU/SEI-96-TR-003). Pittsburgh, PA: Software
Engineering Institute, Carnegie Mellon University, 1996.
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[ECMA 93]
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Reference Model for Frameworks of Software Engineering Environments,
3rd Edition (NIST Special Publication 500-211/Technical Report ECMA
TR/55). Prepared jointly by NIST and the European Computer Manufacturers
Association (ECMA). Washington, DC: U.S. Government Printing Office, 1993.
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[HP 96]
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Integrated Solutions Catalog for the SoftBench Product Family. Palo
Alto, CA: Hewlett-Packard, 1996.
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[JTA 96]
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U.S. Department of Defense. Joint Technical Architecture (JTA)
[online]. Available WWW
<URL:
http://www-jta.itsi.disa.mil/>(1996).
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[Paige 93]
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Paige, Emmett. Selection of Migration Systems ASD (C3I)
Memorandum. Washington, DC: Department of Defense, November 12, 1993.
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[TAFIM 94]
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U.S. Department Of Defense. Technical Architecture Framework For
Information Management (TAFIM) Volumes 1-8, Version 2.0. Reston, VA: DISA
Center for Architecture, 1994. Also available [online] WWW
<URL:
http://www-library.itsi.disa.mil/tafim/tafim.html>
(1996).
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[Temin 96]
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Temin, Thomas, ed. "Mishmash at Work (DoD Systems in Bosnia are not
Interoperable)." Government Computer News 15, 7 (April 1996): 28.
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Darleen Sadoski, GTE
Peter Garrabrant, GTE
Tricia Oberndorf, SEI
10 Jan 97 (original)
The Software
Engineering Institute (SEI) is a federally funded research and
development center sponsored by the U.S. Department of Defense
and operated by Carnegie Mellon University.
Copyright
2008
by Carnegie Mellon University
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URL: http://www.sei.cmu.edu/str/descriptions/tafim_body.html
Last Modified: 24 July 2008
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